High Speed Extrution of Copper and Copper-Zinc Alloys

Abstract

An experimental work of the high speed forward extrusion (ram speed ∼20 m/sec) using the “Dynapak” machine was carried out on Cu and Cu-10∼40%Zn alloys, and the results were analysed in relation to material composition, working temperature and extrusion speed.
The difference in composition yields variations in extrusion behaviors, such as the change in punch stress or velocity during extrusion, the relation between maximum punch stress and extrusion ratio, the temperature dependence of flow stress and the pattern of metal flow. Also, the high speed extrusion shows some different behaviors from those in the case of the slow speed one. For instance, in the former case, a linear relationship is established between maximum punch stress and working temperature, and the punch stress at each temperature successively increases with increasing Zn content (within α-phase). On the other hand, in the latter case, the punch stress changes exponentially against temperature, and its continuous change against Zn content can be seen only over a comparatively low temperature range.